Also known as rubeola or morbilli, measles is an endemic disease, meaning it is continually present in a community, and many people develop resistance.
However, if measles enters an area where the people have never been exposed, the result can be devastating.
Vaccination prevents many cases of measles around the world. The World Health Organization (WHO) estimate that 2.6 million people who have not had the vaccine die of measles every year.
Fast facts on measles
Here are some key points about measles. More detail is in the main article.
- Measles is a highly infectious condition
- Scientists have identified 21 strains of the measles virus
- Symptoms of measles can include watery eyes, sneezing, and a dry hacking cough
- It takes 1 to 3 weeks for the measles virus to establish itself
- There is no specific treatment for measles; prevention is better than cure
- Pregnant women should not take the vaccine
Measles is often noticed through a breakout of spots.
Measles is an infection caused by the rubeola virus.
Its symptoms always include fever and at least one of the three Cs:
- coryza, or runny nose
Symptoms will appear about 9 to 11 days after initial infection.
Symptoms may include:
- runny nose
- dry hacking cough
- conjunctivitis, or swollen eyelids and inflamed eyes
- watery eyes
- photophobia, or sensitivity to light
- a reddish-brown rash
- Koplik's spots, or very small grayish-white spots with bluish-white centers in the mouth, insides of cheeks, and throat.
- generalized body aches
There is often a fever. This can range from mild severe, up to 40.6 degrees Centigrade. It can last several days, and it may fall and then rise again when the rash appears.
The reddish-brown rash appears around 3 to 4 days after initial symptoms. This can last for over a week.
The rash usually starts behind the ears and spreads over the head and neck. After a couple of days, it spreads to the rest of the body, including the legs. As the spots grow, they often join together.
Most childhood rashes are not measles, but a child should see a doctor if:
- a parent suspects the child may have measles
- symptoms do not improve, or they get worse
- the fever rises to above 38 degrees Centigrade
- other symptoms resolve, but the fever persists
Measles is caused by infection with the rubeola virus. The virus lives in the mucus of the nose and throat of an infected child or adult.
The disease is contagious for 4 days before the rash appears, and it continues to be contagious for about 4 to 5 days after.
Infection spreads through:
- physical contact with an infected person
- being near infected people if they cough or sneeze
- touching a surface that has infected droplets of mucus and then putting fingers into the mouth, or rubbing the nose or eyes
The virus remains active on an object for 2 hours.
How does a measles infection develop?
As soon as the virus enters the body, it multiplies in the back of the throat, lungs, and the lymphatic system. It later infects and replicates in the urinary tract, eyes, blood vessels, and central nervous system.
The virus takes 1 to 3 weeks to establish itself, but symptoms appear between 9 and 11 days after initial infection.
Anyone who has never been infected or vaccinated is likely to become ill if they breathe in infected droplets or are in close physical contact with an infected person.
Approximately 90 percent of people who are not immune will develop measles if they share a house with an infected person.
Diagnosis and treatment
Measles gives people with it a fever.
A doctor can normally diagnose measles by looking at the signs and symptoms. A blood test will confirm the presence of the rubeola virus.
In most countries, measles is a notifiable disease. The doctor has to notify the authorities of any suspected cases. If the patient is a child, the doctor will also notify the school.
A child with measles should not return to school until at least 5 days after the rash appears.
There is no specific treatment. If there are no complications, the doctor will recommend rest and plenty of fluids to prevent dehydration.
Symptoms usually go away within 7 to 10 days.
The following measures may help:
- If the child's temperature is high, they should be kept cool, but not too cold. Tylenol or ibuprofen can help control fever, aches, and pains. Children under 16 years should not take aspirin. A doctor will advise about acetaminophen dosage, as too much can harm the child, especially the liver.
- People should avoid smoking near the child.
- Sunglasses, keeping the lights dim or the room darkened may enhance comfort levels, as measles increases sensitivity to light.
- If there is crustiness around the eyes, gently clean with a warm, damp cloth.
- Cough medicines will not relieve a measles cough. Humidifiers or placing a bowl of water in the room may help. If the child is over 12 months, a glass of warm water with a teaspoon of lemon juice and two teaspoons of honey may help. Do not give honey to infants.
- A fever can lead to dehydration, so the child should drink plenty of fluids.
- A child who is in the contagious stage should stay away from school and avoid close contact with others, especially those who are not immunized or have never had measles.
- Those with a vitamin A deficiency and children under 2 years who have measles may benefit from vitamin A supplements. These can help prevent complications, but they should only be taken with a doctor's agreement.
Antibiotics will not help against the measles virus, but they may sometimes be prescribed if an additional bacterial infection develops.
The measles vaccine is widely available and is said to have dropped global rates of measles by over 75 percent.
Complications from measles are fairly common. Some can be serious.
Older people are more likely to have complications than healthy children over the age of 5 years.
Complications can include:
- eye infection
- respiratory tract infections, such as laryngitis and bronchitis
- difficulty breathing
- ear infections, which can lead to permanent hearing loss
- febrile seizures
Patients with a weakened immune system who have measles are more susceptible to bacterial pneumonia. This can be fatal if not treated.
The following less common complications are also possible:
- Hepatitis: Liver complications can occur in adults and in children who are taking some medications.
- Encephalitis: This affects around 1 in every 1,000 patients with measles. It is an inflammation of the brain that can sometimes be fatal. It may occur soon after measles, or several years later.
- Thrombocytopenia, or low platelet count, affects the blood's ability to clot. The patient may bruise easily.
- Squint: Eye nerves and eye muscles may be affected.
Complications that are very rare but possible include:
- Neuritis, an infection of the optic nerve that can lead to vision loss
- Heart complications
- Subacute sclerosing panencephalitis (SSPE): A brain disease that can affect 2 in every 100,000 people, months or years after measles infection. Convulsions, motor abnormalities, cognitive issues, and death can occur.
- Other nervous system complications include toxic encephalopathy, retrobulbar neuritis, transverse myelitis, and ascending myelitis.
Measles during pregnancy can lead to miscarriage, early delivery, or low birth weight. A woman who is planning to become pregnant and has not been vaccinated should ask her doctor for advice.
People who have already had measles are normally immune and they are unlikely to get it again.
People who are not immune should consider the measles vaccine.
In the United States (U.S.), the measles, mumps, and rubella (MMR) vaccine is routinely given at 12 to 15 months of age, followed by a booster shot before entering school at the age of 4 to 6 years.
Newborns carry their mother's immunity for a few months after birth if their mothers are immune, but sometimes the vaccine is recommended before the age of 12 months, and as early as 6 months.
This may happen if they are, or are likely to be, in an area where there is a serious outbreak.
The WHO estimate that measles vaccination programs led to a 79 percent drop in measles deaths globally, from 2000 to 2015, preventing around 20.3 million deaths.
Adults do not require a vaccine in the U.S. if they:
- were born or lived in the U.S. before 1957 in the U.S.
- received two MMR shots after they were 12 months old
- had one MMR vaccine plus a second dose of measles vaccine
- are found to be immune to measles, mumps, and rubella after a blood test
The vaccine should not be taken by:
- women who are pregnant or plan to become pregnant soon
- people with a serious allergy to gelatin or neomycin, an antibiotic
Anybody whose immune system may be compromised by a condition or treatment for a condition should ask their doctor whether they should receive the vaccine.
The CDC points out that during an outbreak of measles in the U.S. between 1989 and 1991, 90 percent of fatal cases were among those with no history of vaccination.
"The most important cause of the measles resurgence of 1989-1991 was low vaccination coverage."
The CDC encourage people to have their children vaccinated, to prevent the spread of measles and the risk of an outbreak.